1. Field of the Invention
This invention relates to a new class of polyols. More particularly, the invention relates to chain-extending existing polyols with epihalohydrin in the presence of a base or alkali metal thereby forming an extended polyol with at least one internal hydroxyl group attached directly to the backbone chain.
2. Description of the Prior Art
It is well known to react polyisocyanates with polyols and, e.g., water, to form flexible polyurethane foams. For the most part, the polyols used in these reactions are triols comprising three backbone chains emanating from a central starter molecule such as glycerol or trimethylol propane and the like. These three chains are relatively uniform in structure and in chain length, each averaging about 1,000 to about 2,000 units of molecular weight. Such molecules can be viewed as comprising a long linear chain having a near centrally attached long chain branch, each leg of which bears a terminal --OH group, for example, ##STR1##
U.S. Pat. No. 3,322,698 discloses rigid cellular urethanes prepared by reacting in the presence of a blowing agent, an organic polyisocyanate and a polyether derived from the reaction of an epihalohydrin and at least one polyol of the formula: EQU HOCH.sub.2 --(CHOH).sub.n --CH.sub.2 OH
wherein n is 1 to 4. The polyether forming reaction is carried out in the presence of an acidic fluorine-containing catalyst, e.g., fluoboric acid, to obtain a polyether containing the group EQU --CH--(CH.sub.2 X)--CH.sub.2 O--
wherein X is fluorine, chlorine or bromine.
U.S. Pat. No. 3,222,300 relates to forming cellular polyurethanes obtained by reacting an organic polyisocyanate with modified polyalkylene ether glycols. The polyalkylene ether glycols bearing solely terminal hydroxyl groups are formed by reacting at least one mole of epoxide or glycidyl ether with a mole of polyalkylene ether glycol.
The polyols of the instant invention have internal hydroxyl groups attached directly to the backbone and no halide present.